AB0675 Health related quality of life in patients with mixed connective tissue disease: A comparison with matched systemic sclerosis patients
Authors: I. Abouyahya, S. Liem, Z. Amoura, J. E. Fonseca, B. Chaigne, M. Cutolo, A. Doria, R. Fischer-Betz, V. Guimaraes, E. Hachulla, T. Huizinga, J. M. van Laar, T. Martin, M. Matucci-Cerinic, C. Montecucco, M. Schneider, V. Smith, A. Tincani, U. Müller-Ladner, J. de Vries-Bouwstra
Journal: Annals of the Rheumatic Diseases (2022)

Background Mixed connective tissue disease (MCTD) is a systemic auto-immune disorder, being probably the least common among the connective tissue diseases. Symptoms can be severe and could affect health-related quality of life (HRQoL). Identification of the burden of MCTD patients is of key importance to provide appropriate pharmacological and non-pharmacological care. No reports on HRQoL have been published in adult patients with MCTD. Objectives To perform an explorative study to evaluate HRQoL and its main determinants in MCTD patients, and compare HRQoL between MCTD and matched systemic sclerosis (SSc) patients. Methods MCTD patients fulfilling the Kahn criteria and participating in the MCTD prospective follow-up cohort of the Leiden University Medical Center were included. In addition, SSc patients matched for age, gender and disease duration were included for comparison. Data on disease characteristics, functional disability and HRQoL were collected annually for both disease groups. HRQoL was evaluated using the 36-Item Short Form Health Survey (SF36) and EuroQol (EQ5D). At baseline, HRQoL, as reflected by SF36 mental component score (MCS), SF 36 physical component score (PCS) and EQ5D were compared between MCTD and SSc patients. For MCTD patients, factors associated with HRQoL at baseline were identified using linear regression and change in HRQoL over 3 years was evaluated using linear mixed models. In addition, characteristics of MCTD patients who showed worsening of MCS and/or had PCS superior to the minimal clinical important difference of three points were identified. Results Thirty-four MCTD patients (121 visits; 82% female, mean age 42 years, median disease duration 45 months) and 102 SSc patients (424 visits; 82% female, mean age 45 years, median disease duration 49 months) were included. At baseline, MCTD-patients more often had ILD (47% vs. 34%, p=0.027), cardiac involvement (30% vs. 2%, p&lt;0.001), synovitis (26% vs. 11%, p=0.004) and myositis (15% vs. 1%, p=0.001) compared to SSc patients, whereas SSc patients more often used immunosuppressive treatments except for hydroxychloroquine (MCTD:18% vs. SSc:7%, p=0.007). Baseline HRQoL in MCTD was comparable to HRQoL in SSc, with mean SF36-PCS of 40.2 (SD:9.1) and mean SF36-MCS of 44.9 (SD:9.9), which is (nearly) one standard deviation lower than the general Dutch population. The SF36 subscore “general health perception” was the most impacted in both groups (MCTD: 38.5 [SD:7.0], SSc: 39.9 [SD:8.9]). The median EQ5DNL was 0.38 (IQR:0.14 – 0.54) and comparable between SSc and MCTD. At baseline, in MCTD, ILD was significantly associated with SF36-PCS (β:6.98, 95% CI: 1.10 to 12.86) and SF36-MCS (β:-8.10, 95% CI:-14.93 to -1.26). Sclerodactyly was significantly associated with EQ5DNL (β:0.006; 95% CI:0.002 to 0.010) and SF36-PCS (β:0.12, 95% CI:0.03 to 0.21). No other significant associations were identified. Over time, in MCTD, both the SF36-MCS and SF36-PCS improved significantly (MCS: β:2.35/year [95% CI:0.58 to 4.13], PCS: β:1.34/year [95% CI:0.03 to 2.65), whereas EQ5DNL was stable. Explorative analyses did not reveal a specific clinical characteristic with significant impact on the change of HRQoL over time. With an MCID of 3 points on the MCS and PCS, 7 MCTD-patients worsened on the MCS and 3 on the PCS. Patients who showed worsening of MCS over time tended to be older, more often had ILD, sclerodactyly and GI complaints, and had worse exercise tolerance. All these differences did not reach statistical significance. The patients who decreased PCS more often had ILD (100% vs. 41%, p=0.015), and used glucocorticoids more often (33% vs. 0%, p=0.046), were slightly older and had a worse exercise tolerance as compared to those who showed a stable/improving PCS over time. Conclusion Like in SSc, HRQoL is significantly impaired in MCTD, especially the general health perception of patients. Cardiac involvement, ILD, age and worse functional disability might specifically impact HRQoL in MCTD. However, these associations need further evaluations in larger cohorts. Disclosure of Interests None declared